1 files changed, 46 insertions, 23 deletions

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index fc0d451279f0..f7c76079f8f1 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -170,6 +170,8 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
 		return NULL;
 	}
 
+	INIT_LIST_HEAD(&tbl->walkers);
+
 	for (i = 0; i < nbuckets; i++)
 		INIT_RHT_NULLS_HEAD(tbl->buckets[i], ht, i);
 
@@ -264,6 +266,7 @@ static void rhashtable_rehash(struct rhashtable *ht,
 			      struct bucket_table *new_tbl)
 {
 	struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
+	struct rhashtable_walker *walker;
 	unsigned old_hash;
 
 	get_random_bytes(&new_tbl->hash_rnd, sizeof(new_tbl->hash_rnd));
@@ -284,6 +287,9 @@ static void rhashtable_rehash(struct rhashtable *ht,
 	/* Publish the new table pointer. */
 	rcu_assign_pointer(ht->tbl, new_tbl);
 
+	list_for_each_entry(walker, &old_tbl->walkers, list)
+		walker->tbl = NULL;
+
 	/* Wait for readers. All new readers will see the new
 	 * table, and thus no references to the old table will
 	 * remain.
@@ -358,7 +364,6 @@ static void rht_deferred_worker(struct work_struct *work)
 {
 	struct rhashtable *ht;
 	struct bucket_table *tbl;
-	struct rhashtable_walker *walker;
 
 	ht = container_of(work, struct rhashtable, run_work);
 	mutex_lock(&ht->mutex);
@@ -367,9 +372,6 @@ static void rht_deferred_worker(struct work_struct *work)
 
 	tbl = rht_dereference(ht->tbl, ht);
 
-	list_for_each_entry(walker, &ht->walkers, list)
-		walker->resize = true;
-
 	if (rht_grow_above_75(ht, tbl))
 		rhashtable_expand(ht);
 	else if (rht_shrink_below_30(ht, tbl))
@@ -725,11 +727,9 @@ int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter)
 	if (!iter->walker)
 		return -ENOMEM;
 
-	INIT_LIST_HEAD(&iter->walker->list);
-	iter->walker->resize = false;
-
 	mutex_lock(&ht->mutex);
-	list_add(&iter->walker->list, &ht->walkers);
+	iter->walker->tbl = rht_dereference(ht->tbl, ht);
+	list_add(&iter->walker->list, &iter->walker->tbl->walkers);
 	mutex_unlock(&ht->mutex);
 
 	return 0;
@@ -745,7 +745,8 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_init);
 void rhashtable_walk_exit(struct rhashtable_iter *iter)
 {
 	mutex_lock(&iter->ht->mutex);
-	list_del(&iter->walker->list);
+	if (iter->walker->tbl)
+		list_del(&iter->walker->list);
 	mutex_unlock(&iter->ht->mutex);
 	kfree(iter->walker);
 }
@@ -767,12 +768,19 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_exit);
  */
 int rhashtable_walk_start(struct rhashtable_iter *iter)
 {
+	struct rhashtable *ht = iter->ht;
+
+	mutex_lock(&ht->mutex);
+
+	if (iter->walker->tbl)
+		list_del(&iter->walker->list);
+
 	rcu_read_lock();
 
-	if (iter->walker->resize) {
-		iter->slot = 0;
-		iter->skip = 0;
-		iter->walker->resize = false;
+	mutex_unlock(&ht->mutex);
+
+	if (!iter->walker->tbl) {
+		iter->walker->tbl = rht_dereference_rcu(ht->tbl, ht);
 		return -EAGAIN;
 	}
 
@@ -794,13 +802,11 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_start);
  */
 void *rhashtable_walk_next(struct rhashtable_iter *iter)
 {
-	const struct bucket_table *tbl;
+	struct bucket_table *tbl = iter->walker->tbl;
 	struct rhashtable *ht = iter->ht;
 	struct rhash_head *p = iter->p;
 	void *obj = NULL;
 
-	tbl = rht_dereference_rcu(ht->tbl, ht);
-
 	if (p) {
 		p = rht_dereference_bucket_rcu(p->next, tbl, iter->slot);
 		goto next;
@@ -826,17 +832,18 @@ next:
 		iter->skip = 0;
 	}
 
-	iter->p = NULL;
-
-out:
-	if (iter->walker->resize) {
-		iter->p = NULL;
+	iter->walker->tbl = rht_dereference_rcu(ht->future_tbl, ht);
+	if (iter->walker->tbl != tbl) {
 		iter->slot = 0;
 		iter->skip = 0;
-		iter->walker->resize = false;
 		return ERR_PTR(-EAGAIN);
 	}
 
+	iter->walker->tbl = NULL;
+	iter->p = NULL;
+
+out:
+
 	return obj;
 }
 EXPORT_SYMBOL_GPL(rhashtable_walk_next);
@@ -849,7 +856,24 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_next);
  */
 void rhashtable_walk_stop(struct rhashtable_iter *iter)
 {
+	struct rhashtable *ht;
+	struct bucket_table *tbl = iter->walker->tbl;
+
 	rcu_read_unlock();
+
+	if (!tbl)
+		return;
+
+	ht = iter->ht;
+
+	mutex_lock(&ht->mutex);
+	if (rht_dereference(ht->tbl, ht) == tbl ||
+	    rht_dereference(ht->future_tbl, ht) == tbl)
+		list_add(&iter->walker->list, &tbl->walkers);
+	else
+		iter->walker->tbl = NULL;
+	mutex_unlock(&ht->mutex);
+
 	iter->p = NULL;
 }
 EXPORT_SYMBOL_GPL(rhashtable_walk_stop);
@@ -927,7 +951,6 @@ int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params)
 	memset(ht, 0, sizeof(*ht));
 	mutex_init(&ht->mutex);
 	memcpy(&ht->p, params, sizeof(*params));
-	INIT_LIST_HEAD(&ht->walkers);
 
 	if (params->locks_mul)
 		ht->p.locks_mul = roundup_pow_of_two(params->locks_mul);